This invention relates to cartons or containers suitable for produce and the like. These cartons are commonly constructed of a corrugated paperboard. More particularly, the invention is concerned with an interlocking bottom closure for a carton. Specifically, the invention relates to an improved self-locking carton bottom which can be efficiently and economically manufactured with minimal waste of material and with minimal cutouts which can jam manufacturing machinery and interfere with removing or "stripping" the box from the machinery.
Corrugated paperboard cartons having a wide variety of construction are well-known in the art. Many of these carton designs employ a plurality of overlapping closure flaps which interlock in various fashions to securely close the top of the carton and a plurality of overlapping bottom closure flaps interlocked to securely close the bottom of the carton. In constructing cartons or containers for fresh fruits and vegetables, it is especially important to provide a strong bottom closure arrangement capable of supporting the considerable weight of the contents.
Frequently the carton manufacturer is located far from where the commodities are to be packed. Thus, as a practical matter, the carton must be capable of being shipped in a flat, collapsed configuration to use shipping and storage space efficiently. Once at the packing location, the flat, collapsed carton must be constructed to be easily fully assembled without requiring skilled personnel or complex equipment. Thus, the action necessary to convert the flat carton from its collapsed condition to its fully assembled state should be performable quickly and simply, preferably without the need to utilize glue, staples or other equipment to secure the carton closure flaps.
For many years, the corrugated paperboard industry has needed a produce box that has a self-locking bottom capable of holding heavy loads such as potatoes, squash, cucumbers, etc. While numerous designs have been tried, these have generally failed in attempting to accommodate heavier loads.
Some bottom closure assemblies have adopted the use of a solid blank bottom, but this requires a large amount of corrugated paperboard in the manufacture and thus is too costly. Another previous approach to enable handling heavy product loads and still have an economical carton was to require the bottom to be glued or stapled, commonly referred to as "stitched." This type carton is not favored as a practical matter because the user does not want to take stitching equipment into the field. Also the user does not want to glue or staple the carton bottoms in advance because these "made-up" cartons require too much room for storage and/or transport to the field location where the produce is being harvested.
U.S. Pat. No. 4,650,112, commonly invented and assigned, discloses a carton for heavy produce and the like having a selflocking bottom which does not require glue or staples. This carton, however, requires a rectangular cutout segment in the minor or width flaps and an L-shaped cutout in the major or length flaps. These cutouts create significant waste problems. They must be collected, packaged, and disposed of at considerable trouble and expense. Of even greater concern, however, is that the cutouts have a tendency to jam or otherwise interfere with the high speed machinery used to manufacture the cartons. The cutouts also have a tendency to inhibit efficient removal or "stripping" of the carton blank from the machinery.